1. Field of the Invention
The present invention relates broadly to earplugs and is more specifically directed to a resilient polymeric multiple flange earplug construction useful as a hearing protector.
2. The Prior Art
In the United States one of the better known earplugs of the general type contemplated by the present invention is that known as the "V-51 R", the construction details of which earplug are disclosed in a report entitled Development of an Extra Small and Extra Large Size for the V-51 R Earplug, D. T. Blackstock and H. E. Von Gierke, April 1956, Aero Medical Laboratory, Wright Air Development Center, Air Research and Development Command, United States Air Force, WADC Technical Report 56-142. This earplug was developed during the course of World War II in order to provide improved hearing protection to members of the military who are subjected to concussive sounds, such as gunfire or explosions or to extremely noisy work environments, such as at airports or aircraft maintenance facilities. The V-51 R earplug is composed of a resilient elastomeric material, such as neoprene rubber, and comprises a single retroverted flange element extending from the nose end of a tubular rubber stalk member. The flange element extends rearwardly from the nose of the tubular rubber stalk and is so spaced therefrom as to provide a free annular space therebetween. In use, the earplug is forceably inserted into the ear canal, thereby at least partially collapsing the rearwardly extending flange element into the underlying free annular space and conforming said flange element into an acoustic sealing relationship with the constraining walls of the ear canal.
In U.S. Pat. No. 2,427,664, J. Y. Dunbar and J. S. Knight, Sept. 23, 1947 and U.S. Pat. No. 2,717,596, J. S. Knight, Sept. 13, 1955, there are disclosed earplugs similar to the V-51 R earplug described in the aforementioned Blackstock et al. report. In FIGS. 2 and 3 of U.S. Pat. No. 2,427,664, there is additionally depicted an earplug comprising four disk-shaped flange elements of serially increasing diameters extending substantially transversely of the supporting stalk member. As is most clearly seen in FIG. 3, all four flange elements of the construction are disclosed to be insertable into the ear canal and are biased somewhat rearwardly by the constraining walls thereof.
Unfortunately, earplugs of the type disclosed in the foregoing publications and in those variants thereof known to the present applicant are often possessed of several disadvantages. Firstly, when properly worn a certain significant proportion of the wearer population often experiences discomfort in the use of such plugs. Generally this discomfort is perceived as a sense of excessive pressure being brought to bear on the walls of the ear canals, which pressure can be of such magnitude as to be painful. A common user response to such discomfort is to withdraw the offending earplug from the ear canal to the point where the perceived excessive pressure is relieved and, when this is done, as often as not the acoustic seal between the plug and the ear canal is broken or weakened, thereby destroying or at least compromising the intended hearing protection function of the earplug. This is a particularly pernicious deficiency because, while the subject person involved may seem from outward appearances to be suitably hearing protected in fact, he or she may not be protected at all. Secondly, due to the well known anatomic variability of sizes and shapes of ear canals throughout the population, including the variability which often exists as between the ear canals of an individual user and the variations in size of individual ear canals which occur naturally, it is generally required that flanged earplugs be produced in a number of sizes and that they be carefully fitted by trained personnel in order to assure the attainment of competent hearing protection. For instance, the V-51 R plug mentioned above is presently produced in five different discrete sizes which, according to the aforementioned Blackstock et al. report, provides the ability to properly fit 80-85% of the adult male user population therewith. Obviously, the requirement to produce multiple sizes of an earplug adds greatly to the cost and complexity of manufacture thereof. In accordance with the present invention, however, there is provided a multiple flange earplug which can be produced in a single size and yet comfortably fit and provide effective hearing protection for the great majority of the population.